CompatHelper: bump compat for DSP to 0.8, (keep existing compat)

This pull request changes the compat entry for the `DSP` package from `^0.7` to `^0.7, 0.8`. This keeps the compat entries for earlier versions. Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.